1. Field of the Invention
The invention relates to thermophilic phospholipases and a method for producing the phospholipases. More particularly, the invention relates to novel thermophilic phospholipases useful in degumming processes and widely applicable to the oil chemical industry and the pharmaceutical industry, as well as a method for producing the phospholipases.
2. Description of Prior Art
To date, phospholipase A.sub.2 has been used as an agent for treating hypercholestelemia [J. Lipid Res. 36, 1147 (1995)], and phospholipase A.sub.1 and phospholipase A.sub.2 have been used for production of lysophospholipids useful as a surfactant [J. Am. Oil Chem. Soc. 72, 1375 (1995)].
Phospholipase A.sub.2 has also been used in oil refining processes. When phospholipase A.sub.2 is introduced into degumming processes in oil refining, it becomes possible to reduce the phosphorous content to a level of 8 ppm or below, and thus simple physical oil refining processes become applicable. As a result, the oil refining process using phospholipase A.sub.2 is used in its degumming processes has successfully reduced the amount of water consumption to 1/8 based on that of conventional processes and the steam cost to 5.27 dollars/ton which was 9.19 dollars/ton in conventional processes (Inform, 6, 1284 (1995)).
As mentioned above, phospholipases have been widely used in various fields. However, since such phospholipases are originated from higher organisms, they are limited in yield and properties such as thermostability. In particular, in these processes, in which high temperature circumstances are desired such as degumming processes in oil refining, thermophilic phospholipases which do not lose their enzymatic activity even at high temperatures have been strongly demanded.
However, such thermophilic phospholipases have not been reported yet.